1. Field of the Invention
The present invention relates to a technology for measuring intensity, phase, and direction distributions of electric fields occurring inside or outside a measurement object.
2. Description of the Related Art
In order to identify positions and propagation paths of electromagnetic energy in an electronic apparatus causing malfunctions and the like due to electromagnetic mutual interference, it is required to measure intensity, phase, and direction of electric fields or magnetic fields generated from the electronic apparatus in a two dimensional or three dimensional manner.
Heretofore, the present inventors have invented a magnetic field measuring antenna or a measuring method and apparatus as disclosed in Japanese Patent Laid-open Publication No. 2002-156430 and Japanese Patent Unexamined Publication No. 2003-279611 (and its International Publication WO03/081265 A1). Of the same, the former relates to the magnetic field measuring antenna and the latter relates to the measuring method and apparatus.
In general, when the intensity, phase, and direction of an electric field generated from an electronic apparatus as a measurement object are measured in a two-dimensional or three-dimensional manner, an electric field antenna having directivity and a known antenna coefficient, the coefficient whereby an induced voltage in the antenna and an electric field intensity at the antenna position are mutually related in one-to-one correspondence, is used and the antenna is disposed at an optional measurement position around the measurement object. Thereby, a current or voltage induced in the antenna is measured, and, based on the results of the measurement and the antenna coefficient, a spatial distribution of the electric field intensity and its direction at the measurement position can be obtained. At this time, it is imperative that the disposition of the antenna at the desired measurement position has little effect on the distribution of the electric field generated from the electronic apparatus.
As the antennas for measuring electric field intensity and direction in a space, monopole antennas, dipole antennas, Yagi antennas, and the like are generally used. Of these antennas, dipole antennas and Yagi antennas are difficult to be miniaturized in their physical dimensions and hence difficult to achieve high resolution. Accordingly, monopole antennas that are easily miniaturized have been in use for measurement of electric field distribution around such small-sized electronic devices as LSI chips.